Date post: | 11-May-2015 |
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General Medicine for the Optometrist
Dr Russell Watkins
Anaemia Not a single disease state, anaemia
results from a precipitating pathological process
It is defined as a reduction in the concentration of circulating haemoglobin Defective Hb synthesis Diminished RBC production Excessive RBC destruction Blood loss
Anaemia Ocular features of anaemia due to any
cause Pale conjunctivae Retinal haemorrhages Roth spots Dilated retinal veins
Sickle Cell Disease Caused by the presence of one or more
abnormal haemoglobins RBCs adopt abnormal “sickle” shape
under conditions of hypoxia & acidosis Sickled RBCs cause hypoxia by blocking
arterioles multi-tissue & multi-organ damage
Sickle Cell Disease
AS (sickle cell trait): requires hypoxia or abnormal conditions to produce sickling
SS (sickle cell disease): severe systemic complications, mild ocular disease
SC (sickle cell HbC disease): severe ocular disease
Sthal (sickle cell Hb with thalassaemia): severe systemic & ocular disease
Sickle Cell Disease Ocular features (anterior segment)
“Comma-shaped” vascular segments seen on conjunctivae
Focal ischaemic atrophy of iris; occasional hyphaema & rarely rubeosis
Sickle Cell Disease Posterior segment involvement
Venous tortuosity Peripheral choroidoretinal scars (black
sun-bursts) Salmon patch haemorrhages “Silver-wiring” of peripheral arterioles Retinal breaks Angioid streaks
Sickle Cell Disease Posterior segment involvement (cont.)
Vascular occlusions C/BRAO and C/BRVO
Sickle retinopathy produces “sea-fan” pattern neovascularisation eventually causing vitreous haemorrhage & traction retinal detachment
Demyelinating Disease A group of diseases in which the main
abnormality is damage to the CNS myelin The most important condition is multiple or
disseminated sclerosis MS is an immune-mediated disease of
uncertain aetiology Relapsing episodes of demyelination within
the CNS Episodes separated in time & space Demyelination leads to failure of axonal
function producing neurological defects
Demyelinating Disease Demyelination occurs in the brain & spinal
cord Areas of demyelination are called plaques
Histology (acute stage) = lymphocyte cuffing around small vessels; lipid-laden foamy macrophages & enlarged astrocytes are seen around the plaque
Most axons spanning a plaque are preserved thought there is evidence that there is some axonal loss
Histology (later) = few inflammatory cells; astrocytes occupy plaques
Demyelinating Disease Epidemiology
Onset most often at age 20-40 yrs Said to more common in middle class
women More common in northern climes RBN more commonly occurs in the
spring Associated with HLA-DR2
Demyelinating Disease Diagnosis is based on
History Examination Investigations
Electrophysiology MRI scans Cerebrospinal fluid examination
Demyelinating Disease Ocular features
Retrobulbar & optic neuritis Eye movement disorders
Nerve palsies incl. ptosis INO Nystagmus
AAU
Tumours of the Nervous System
Primary neoplasia are an important cause of death in young people - ~10% of cancer deaths in those aged 15-35yrs
Most common neoplasm in the brain is metastasis
Others Meningiomas Gliomas Lymphomas
Clinical Features of ICP In slowly developing lesions, symptoms
& signs may develop slowly In rapidly progressive lesions, symptoms
& signs can develop within minutes There may be vomiting, headache and
papilloedema When more advanced, there may be a
‘blown pupil’, bradycardia, hypertension and dyspneoa (due to neurogenic pulmonary oedema)
Cerebrovascular Disease The third most common cause of death
in Western countries Most frequent manifestation is the
sudden onset neurological deficit known as “stroke”
Stroke can be due to infarction or haemorrhage (85%:15%)
Cerebrovascular Disease Stroke occurs in about 2 per 1000
population The clinical spectrum of the
cerebrovascular accident Stroke Reversible ischaemic neurological
deficit (RIND) Transient ischaemic attack (TIA)
Cerebrovascular Disease Definitions
Stroke is a sudden onset, non-traumatic focal neurological deficit which causes death or lasts longer than 24 hrs
A RIND is when function returns after a period of time (usually defined as 7 days)
TIAs are defined as non-traumatic focal loss of cerebral or visual function lasting less than 24 hrs
Cerebrovascular Disease Glutamate receptor activation
Ischaemic damage causes activation of the NMDA subtype of glutamate receptors
Calcium ions pour into the neurons causing cell death
This process is termed excitotoxicity & is also believed to be implicated in the optic neuropathy of open angle glaucoma
Cerebrovascular Disease Sub-arachnoid haemorrhage is most
often due to rupture of a berry aneurysm (present in about 2% of population)
“Thunderclap” headache Associated with subhyaloid
haemorrhage
Site of aneurysm
Seronegative Arthropathies Characterised by
Spinal & sacroiliac joint involvement Asymmetrical oligo- or monoarthritis
of large joints Strong HLA associations Extra-articular manifestations
(including ocular)
Seronegative Arthropathies Ankylosing spondylitis Reiter’s syndrome Behçet’s disease Psoriatic arthropathy Enteropathic arthropathies (Juvenile chronic arthritis)
Ankylosing Spondylitis Progressive spinal fusion with loss of
mobility; pulmonary fibrosis; aortic regurgitation; colitis
M>F; 90% HLA-B27 positive Prevalence 1 in 2000 Associated with uveitis, scleritis,
episcleritis
Reiter’s Syndrome Triad of conjunctivitis/iritis/keratitis,
arthritis & urethritis/dysenteric disease M>>F; 70% HLA-B27 positive; 30% AAU Arthritis affects knees, sijs, ankles Plantar fasciitis Keratoderma blenorrhagica on feet &
hands Circinate balanitis Painless mouth ulcers
Behçet’s Disease Triad of oral ulceration, genital
ulceration, inflammatory eye lesions M>F esp Japan & Mediterranean
(Turkey) Increased prevalence of HLA-B5
Behçet’s Disease Ocular features
Severe AAU (often with hypopyon) Conjunctivitis Keratitis Episcleritis Retinal vasculitis & infarction BRVO Neovascularisation with vitreous
haemorrhage Retinal & macular oedema & exudates
Psoriatic Arthropathy Increased prevalence of HLA-B17 &
HLA-B27, associated with Conjunctivitis AAU Dry eyes
Enteropathic Arthropathy Ulcerative colitis & Crohn’s disease
Inflammatory bowel diseases with systemic manifestations
Ocular features Conjunctivitis, KCS,
keratoconjunctivitis, episcleritis, scleritis, AAU, retinal oedema, orbital cellulitis, optic neuritis
Juvenile Chronic Arthritis A multisystem seronegative disease
that also has ocular manifestations Chronic anterior uveitis Secondary glaucoma Cataract Band keratopathy